Mid-latitude Spread F long-term occurrence characteristics as a function of latitude over Europe

Abstract

Mid-latitude spread F has been investigated in past studies, mostly over the Southern Hemisphere. It has been correlated with geomagnetic activity, travelling ionospheric disturbances (TIDs) and F region uplifts, with Perkins instability proposed as the primary seeding mechanism. In this paper, we focus on the latitude effect on the diurnal and seasonal occurrence rate of mid-latitude spread F over the two stations of Nicosia (geographic Lat: 35.29°N, Long: 33.38°E) and Moscow (geographic Lat: 55.50°N, Long: 37.30°E) that reside over the same longitude sector. The period of investigation encompasses a full solar cycle extending from 2009 to 2020. We observe remarkable differences in spread F occurrence characteristics over the two stations both seasonally and diurnally, emphasizing the fact that higher and lower mid-latitude stations over European latitudes are governed by different underlying mechanisms that give rise to spread F events.